Switch



Patented Jan. 3, 1933 UNITED STATES .means y '.rOMLrNsON r. JOHNSON, `or ATLANTA, GEORGIA SWITCH Application ined January 1a, 1,931. serial No. 508,309.

This invention relates to electrical switches such as are used on high voltage transmission systems and, among other objects, aims to provide an improved, high-pressure Contact for air-brake switches of the jaw and blade or knife type. The main idea is to provide a strong, durable and relatively cheap switch having a great current carrying capacity and provided with means whereby the circuit may be made and broken by a powerful lever action so that the blade is self-cleaned and will clear the contacting parts of considerable ice.

Other aims and advantages of the inventionrwill appearin the specification, when considered `in connection with the'accomf panying drawing, wherein: Y

Fig. 1 is a fragmentary side elevation of a single switch embodying theinvention;

Fig. 2 is a top plan view of the contact parts shown in Fig. 1,; and

Fig. 3 is an end elevation.

Ordinary high tension switches usually have large spring jaws presenting Hat contact surfaces for the flat ends of switch blades. Insuch switches, the springpressure on the jaws is generally quite small so that the bladescan easily be manipulated to make and 'break the circuit. The current carrying capacity of low-pressure contacts is directly proportional to the contacting areas. Hence, the contact elements, including the blades and jaws, are necessarily large and expensive. High pressure, clean contacts wi-ll carry heavy loads and their capacity is not dependent upon contact .area but increases in proportion to the pressure within limits.

This invention therefore provides an improved high pressure contact which enables the parts to be made much smallerthan the ordinary surface contactelements of the same current carrying capacity.

In this example. the illustrated improvements are applied to a horizontal air-.break switch, but it will be understood that the invention is equally applicable to vertical switches. In fact, either type of switch may be used interchangeably.

Referring particularly tothe drawing, the jaws are mounted on a bracket 10 which is adapted to be secured lon the top Aof an ordil nary pin-type insulator l(not shown). The bracket has an arm 11 to which a conductor is adapted to be secured in the usual manner. On the top of the bracket is secured a tfransverse spring plate 12 which may be made'of a rust-proobronze having thin'copper plates 13 applied to both sides to increase the conductivity. The thickness of-{the plate is determined by its vlength and the amount of spring pressure vto be exerted on the jaws. On the opposite end portions of the plate are secured jaw elements 14 andl so shaped as to provide the usual laredbightportion 3 between them to'guide they switch blade. The 65 jaw 14 basa horizontal contact arm 16 which is cut away slightly to aord blade clearance` at the inner end of itsy contacting lower face and the jaw 15 has a rearwardly projecting al contact arm 17 opposite the arm 16 and 70 terminating short` of the vertical leg of the jaw 14;. The end ofl the arm 17 is shown as having an integral vertical iiange 18 to provide a combined stop and guide for the j switch blade. As shown in Figs. 1 and 2, 75 the Aflange projects outwardly beyondv the jaws so that its outer end will act as a ulcrum for releasing the blade'as [hereinafter described. The jaws are shown as having integral, rearwardly extending fingers or projections 19 and 20 extending beyond the end of the Harige 18 and having a` transverse fulcrum pin 21 secured in Openings ,inv their outer ends. This pin serves as a ulcrum or abutment for the outer end Ot the blade to give it powerful leverage when'it is. being closed, as will be described. The projecting end of the flange 18 `is integrally connected to the ringer 20 so that the finger acts .as a reinforcing or strengthening flange.

The blade is of the toggle or ointed type, conveniently being made `of a pair of spaced parallel copper bars 22 constituting one leg and a cast copperor bronze tip 23 constituting the other leg, the tip being pivoted between the ybars on a bolt 424. A wire spring 25 having coils 26 on one end of the bolt is connected normally to break the knee joint so that the legs assume the relative angular positions shown by the dotted lines in Fig. 2.l

` because it initially has line instead of surface. v

The pivoted end of the blade tippreferably has a stop lug 27 arranged to strike a stay pin 28 between the bars 22 and thus limit the relative swinging movement of the tip.

In Figs. 1 and 3 the blade tip is shown as having a thickened contact portion 29 which has its opposite faces rounded or curved so that Vit is more `or less ellipticalshaped in cross section and will'more easily enter the bight portionV ofthe jaws. Moreover, this shape reduces the sliding friction between the 'blade and the faces of the jaws contact with the jaw faces. Further, the concentrated rubbing 'action will clean the jaw faces and the blade and insure good metal to metal contact. Y Y

The blade tip is shown as having a reduced extension or lever arm 30 adapted to strike the vertical flange 18 as the blade closes so as to be guided behind the fulcrum pin 21 upon the initial closing movement due to the straightening of the knee joint. As the contact portion 29 enters the jaws and the lever arm strikes the flange 18, the knee joint begns to straighten and the lever arm 3() swings against the pin 21 about the jaws as a pivot. Further, closing movement of the blade forces it into the jaws by a lever action, the lmechanical advantage of which is measured by the ratio between the distance from the fulcrum pin 21 to the knee joint or axis of the bolt 24 and the distance from the fulcrum pin to the middle of the jaw faces. In this instance, the ratio is about 3 to 1, but it may be varied according tothe size of the switch and the pressure exert-ed by the jaws. Hence, the force necessary to be applied manually to close the blade need not be any greater than that exerted on the common type of switch.

n As the blade closes and the knee joint straightens the contact portions 29 move about the pinv 21 as a pivot and also move longitudinally outwardly. This compound movement enables the contact faces to wear themselves clean where they rub against the jaw faces.

`When the blade is opened, the knee joint breaks first and the lever arm 30 swings into contact with the outer end of the flange 18 which then acts as a fulcrum. The mechanical advantage is now suiiiciently great to move the blade very easily so that it will clear the jaws and itself of any ice that may be formed on them.

Since thehigh pressure contact is the subject of this'invention, itis not necessary to describe the operating mechanism for the blade or a series of blades of a gang switch.

'Y Each blade is usuallymounted on an ordinary threaded through the bars 22 to carry the current between the knee joint and the line conductor beyond the pivoted insulator.

From the foregoing description, it will be seen that the improved switch is relatively simple; that there are only a few parts which require machine operations; that the size and weight of the parts are considerably less than the sizeand weight of the parts of the ordinary switches having the same capacity; and that the cost of manufacture is considerably reduced.

Obviously, the present invention is not restricted to the particular embodiment thereof herein shown and described. Moreover, it is not indispensable that all the features of the invention be used conjointly, since they may be employed advantageously in various combinations and sub-combinations.

What is claimed is:

1. In an electric switch of the character described, a pair of spring jaws having associated transverse fulcrum means; and a toggle-jointed switch blade having a contact tip with an integral extension arranged to engage behind the fulcrum means upon openf ing and closing movement of the blade so that the contact elements are engaged and disengaged by a lever action.

2. In a knife switch of the class described, a jointed blade; a pair of spring jaws to receive the blade and arranged to provide a high-pressure contact; lever means on the blade; and a transverse fulcrum on the jaws coacting with the lever means automatically to increase the closing force applied to tbe blade during the final stages of its Vclosing movement. Y

r3. In a knife switch of the class described, a jointed blade; a pair of jaws to receive the blade and arranged to provide a high-pressure contact; fulcrum members associated with the jaws; and a lever member on the blade arranged to engage one fulcrum member when the contact portion of the blade approaches its closed position so as to increase the closing pressure and to engage another fulcrum member as the blade begins to open so as to increase the opening force until the blade clears the jaws.

4. In an electric switch of the class described` a pair of high-pressure contact jaws; a toggle-jointed blade; a lever projection on the end of the blade: and a transverse fulcrum member supported b v the jaws in the path of movement of the blade and so arranged that the lever projection engages behind it after the blade tip strikes the j aws and the knee joint of the toggle begins to straighten whereby to increase the nal closing pressure applied to the blade.

5. In an elect-ric switch of the class described. a pair of hi gli-pressure contact aws;

projecting rearwardly from the jaws; and a tran-sverse fulcrum pin carried by the arms and arranged in the path of movement of the lever projection so that the lever engages behind the pin as the blade tip approaches closed position andthe knee joint of the toggle begins to straighten due to the resistance offered by the jaws whereby the final closing pressure is greatly increased.

6. In an electric switch of the class `described, a pair of high-pressure Contact jaws; a toggle-jointed blade having a spring normally to break the knee joint; arms project-k ing from the jaws; a fulcrum pin mounted in the arms across the path of the blade; a combined blade abutment and fulcrum member adjacent to the bottom of the jaws; a lever projection on the end of the blade arranged to engage said fulcrum pin during the nal closing movement of the blade and to engage the fulcrum member when the blade is being initially opened.

7. In an electric switch of the class described; a. jaw supporting bracket; a spring y plate secured between its ends on the bracket; jaws mounted on the opposite end portions of the plate; a. toggle jointed blade presenting rounded Contact portions to havehigh-pressure line contact with the jaw faces; a ulcrum flange projecting from one of the jaws; a fulcrum pin carried by the jaws; and a lever projection on the end of the blade arranged to engage said fulcrum pin upon final closing movement of said fulcrum flange upon initial opening movement.

8. In a horizontal knife switch of the class described, a jaw-supporting bracket; a horizontal spring plate secured between its ends to the bracket; a pair of jaws secured to the end portions of said spring plate; a flange on one end of the jaws providing a limiting stop Jfor the blade and extending rearwardly from the jaws in the path ofJ movement of the blade to provide a fulcrum; rearwardly projecting parallel arms on the jaws; a fulcrum pin on the ends of said parallel arms; a togglejointed blade having a contact portionvof substantially elliptical cross section; a spring connected normally to break the knee joint of the blade; stop means to limit the angular movement of the jointed legs; and a lever projection on the end of the blade arranged to be projected behind said fulcrum pin after the contact portion of the blade strikes the jaws and the knee joint begins to straighten whereby the blade is finally closed by a powerful lever action, said lever also being arranged to engage the rearward extension of said flange when the blade is initially opened and the knee joint begins to break so that the blade is released by a powerful lever action. In testimony, that I claim the foregoing as my own, I have hereto affixed my signature.

TOMLINSON F. JOHNSON. 

